The device of this invention lies in the field of envelopes for shipping documents or other items which are to be transported within packages or containers. It more specifically applies to envelopes which can be attached to containers which can easily receive documents as the container is filled and easily opened at its destination.
Many different types of shipping envelopes have been developed and used with varying degrees of success and with various disadvantages and difficulties.
In one prior art form an envelope is made up of two sheets of transparent plastic material secured together along sides and one end, the front panel being somewhat longer than the back panel. The excess length of the front panel is coated with pressure sensitive adhesive on its rear face and the back panel is similarly coated, with sheets of release material protecting the adhesive and preventing premature sticking. In use, the shipping documents are placed in the envelope, preferably with an address showing through the front panel, the release sheets are removed, and the envelope and the flap extending outward are pressed against the package to secure it in place. The only seal of the envelope opening is the adhesion of the envelope and flap to the surface of the container. Examples of this form are shown in U.S. Pat. Nos. 3,327,416 to Sanford and 3,525,470 to Carrigan.
Other forms include a gummed paper frame overlying the margins of a letter or envelope and secured all around to a carton, as shown in U.S. Pat. No. 3,159,130 to Allen.
With the first type, one or more documents are placed in the envelope and thereafter it is secured to the carton. If the carton or crate is large, and parcels are placed in it at separate times, the envelope must be kept loose, but handy somewhere nearby to receive documents from time to time until the package is filled, after which the envelope is secured to the package. Because it is sealed to the package all around, it is quite difficult to remove or open at the destination. The other forms require accurate centering of the frames or sheets over the papers and are similarly difficult to open or remove at the destination.
What is needed is a shipping envelope which may be secured to a carton while still empty to prevent misplacement and with an open and free marginal edges to allow a plurality of papers to be inserted from time to time as the carton is gradually filled, together with a flap which may be folded under the mouth to secure the contents and then itself sealed to the surface of the carton. In addition, the envelope should be easy to open upon arrival at the destination.